1. Field of the Invention
The present invention relates to image processing techniques, and in particular to an apparatus for coordinating data transmission between a data providing device and a display device.
2. Description of the Prior Art
The thin film transistor LCD (TFT LCD) is one of the most popular displays at the present day. As known by those skilled in the art, for TFT LCDs, the interfaces of receiving external image data can be roughly divided into two classes: RGB interface and CPU interface. In addition, the transmission modes of the external image data can be classified into single transmission modes, two-time transmission modes, and three-time transmission modes.
Please refer to FIG. 1(A), which illustrates an example of the image data of a pixel. In this example, the pixel is represented by 24 bits of data including eight bits of red data (R0˜R7), eight bits of green data (G0˜G7), and eight bits of blue data (B0˜B7). As shown in FIG. 1(B), under the single transmission mode, the 24 bits of data are transmitted to a TFT LCD in one transmission duration. Under the two-time transmission mode, the 24 bits of data are divided into two groups; the two groups are transmitted to a TFT LCD in two different transmission durations. Under the three-time transmission mode, the 24 bits of data are divided into three groups respectively transmitted to a TFT LCD in three different transmission durations.
Under some conditions, the resolution of the display is lower than the number of bits provided by a data providing device (e.g. CPU). For instance, although the data providing device provides 24 bits of data to represent each pixel, the resolution of the display may only be 18 bits (respectively 6 bits of red, green, and blue). Therefore, the two least significant bits of each color (e.g. R0 and R1 for red) must be abandoned. Taking the two-time transmission mode for example, the 18 bits of data which is finally transmitted to the display is shown in FIG. 1(C).
To adjust data provided by a data providing device into the formats required by a display, there is usually a coordinating circuit between the data providing device and the display. The coordinating circuit is responsible for selecting and arranging image data needed by the display.
In prior arts, to satisfy different requirements of different displays, designers of the coordinating circuit must provide various kinds of coordinating circuits at the output end of a data providing device. Once the data providing device is going to cooperate with a new display/transmission specification, the designers must re-design or re-organize the circuits, so as to provide the corresponding coordinating function. Much cost and time are accordingly wasted.